I played a game with this, It does feel more like previous civ's than civ5 did.

ICS is viable (actually, there is no downside to ICS), chop everything, flip cities with culture. Well, not culture, but influence: cities have a sphere of influence, so if you settle too close to a different civ you have to be prepared that your city will flip. In my game this netted me four cities: one captured CS close to some of my big cities, a city within a few tiles of my opponent's capital (WHAT), and two newly settled size 1 cities.

I didn't like the golden age/dark age system: you have to trigger events (like building something, or completing a trade route), but it's not clear to me what the strategy is to succesfully trigger these events. The triggers differ from era to era as well. In some era's I got a golden age without even trying. I suspect that once you have figured this out it's just a way to get an advantage over the AI.